Clutch control apparatus for hybrid vehicle

Abstract

A clutch control apparatus for a hybrid vehicle (1) having an engine (2) and a motor (3) as power sources, and an output shaft (13a). The clutch control apparatus includes a clutch device (12) and a clutch control device (19) operatively connected to the clutch device (12) for controlling the engagement degree of the clutch device (12) when the driving mode of the vehicle is alternately switched between an engine cruise mode and a motor cruise mode. The clutch control device (19) is adapted to execute a clutch relaxation control operation which includes an engagement decreasing control operation and a subsequent engagement recovery control operation, and is further adapted to execute an engagement increasing control operation in which the engagement degree of the clutch device (12) is forced to increase when the revolution rate of the engine (2) falls below a predetermined value.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a clutch control apparatus for a vehicle, generally known as a hybrid vehicle, which includes, as power sources, an engine and a motor, the vehicle obtaining driving power from at least one of the engine and the motor. [0003] Priority is claimed on Japanese Patent Application No. 2002-334991, filed Nov. 19, 2002, the content of which is incorporated herein by reference. [0004] 2. Description of Related Art [0005] In recent years, in order to conserve fuel in the running of engines, or to reduce exhaust gas produced by combustion of fuel, hybrid vehicles have been developed, each of which includes an engine and a motor, the motor also being capable of generating electrical energy (hereinafter referred to as a motor-generator) that are connected to a power transmission mechanism connected to driving wheels, and in which the motor-generator produces supplemental driving power depending ...

AI Technical Summary

Benefits of technology

[0011] In view of the above circumstances, an object of the present invention is to provide a clutch control apparatus for a hybrid vehicle, by which drivability of the vehicle is improved, and vehicle behavior is stable even when the drive mode of the vehicle is switched back and forth between an engine cruise mode and a motor cruise mode.

Problems solved by technology

Conventionally, in such a hybrid vehicle, the motor-generator is not used solely for driving the vehicle (hereinafter this driving mode is referred to as a “motor cruise mode”) because, in a motor cruise mode, the engine is a portion of the load for the motor-generator, and the motor-generator must produce power to compensate for the pumping loss and friction of the engine; therefore, fuel efficiency may not be improved when compared with the case in which the engine is used solely for driving the vehicle (hereinafter this driving mode is referred to as an “engine cruise mode”).

However, in such a hybrid vehicle which may be driven by a motor, a problem is encountered in that an unexpected deceleration feeling (hereinafter referred to as a drag feeling) or jolt is experienced when the driving mode of the vehicle is alternately switched between the motor cruise mode and the engine cruise mode.

More specifically, when the driving mode of the vehicle is switched from the engine cruise mode to the motor cruise mode, a drag feeling is experienced due to cut of fuel supply to the engine along with a jolt (vehicle vibration) due to changes in the engine friction by stopping the operations of the intake and exhaust valves.

On the other hand, when the driving mode of the vehicle is switched from the motor cruise mode to the engine cruise mode, another drag feeling is experienced due to changes in the engine friction by starting the operations of the intake and exhaust valves along with a combustion initiation jolt due to start (ignition) of the engine operation.

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